SOD was characterized in 1968 by McCORD and FRIDOVICH; it is an enzyme which promotes removal of the superoxide radical (O.sub.2.sup.-), constitutes a priori a mechanism of protection against the deleterious effects of this radical, is capable of being formed in vivo from atmospheric oxygen and therefore plays a major role in preventing the toxic effects which could result from exposure to an oxygenated atmosphere.
As free radicals derived from oxygen seem to be involved in numerous complaints, the use of SOD in therapeutics has therefore been recommended in inflammatory arthropathy (R. NORDMANN et al., Cah. Nutr. Diet., 1991, 26, 6, 398-402); SOD has also been proposed with a greater or lesser degree of success in pulmonary diseases, more particularly bronchopulmonary dysplasia, or in other toxic conditions associated with the presence of substantial amounts of oxygen (central nervous system, ischaemia, non-vascular gastro-intestinal disorders, ocular disorders (locally in the anterior chamber of the eye) or control of the undesirable effects of anticancer treatments) (GREENWALD R. A., Free Radical Biol. Med., 1990, 8, 201-209).
SOD, in its liposomal bovine Cu/Zn form, has been found to be particularly effective on radiofibrosis in clinical trials (Baillet F. et al., Treatment of radiofibrosis with liposomal superoxide dismutase. Preliminary results of 50 cases, Free Rad. Res. Commun., 1, 387-394, Harwood Academic Publishers GmbH, 1986) and subsequently in experiments on pigs (Lefaix J. L. et al., La fibros cutaneo-musculaire radio-induite: efficacite therapeutique majeure de la SOD Cu/Zn liposomiale (Radioinduced cutaneomuscular fibrosis: major therapeutic efficacy of liposomal Cu/Zn SOD), Bull. Cancer, 1993, 80, 799-807), these results being all the more interesting because there is no product which has an equivalent action.
Of the SODs tested, those which have an extended half-life and a low incidence of immunological illnesses are preferred; the following may be mentioned in particular: Cu/Zn SOD of bovine origin (a homodimer which catalyses the dismutation of the superoxide radical), Mn SOD, Fe SOD, liposomal SODs, SODs conjugated with polyethylene glycol, SOD polymers or copolymers and recombinant human Cu/Zn SOD and Mn SOD.